Chapter 3: The Functional Groups and Their Functions
3.3 ALKENES
An alkene is a molecule with no functional groups present and at least
one double bond between any two of the carbons in its backbone.
Alkene molecules usually have names that end with the suffix –
ene. For instance, alpha-pinene, sabinene, limonene, and gamma-
terpinene are examples of monoterpene alkenes. Germacrene D,
beta-caryophyllene, zingiberene, and alpha-cedrene are examples
of sesquiterpene alkenes. Each of the molecules in figures 2.3 and
2.4 are alkenes: they have no other functional groups and at least
one double bond between carbons. In fact, most of these molecules
have many double bonds.
Monoterpene and sesquiterpene alkenes are well-known for their
antioxidant properties.* The large number of double bonds and the
existence of ring structures in these molecules makes them excel-
lent at accepting the lone electrons contained in free radicals.
Properties of Alkene Containing Constituents
Aromatic: Many unique and pleasant fragrances
Topical: Antioxidant benefits for the skin and the tissues
Internal: Antioxidant benefits for the internal organs, may also sup-
port the nervous, immune, digestive, reproductive, integumentary,
and circulatory systems*
Oils high in monoterpene alkenes: Frankincense, Douglas Fir, Blue
Tansy, Lemon, and Wild Orange
Oils high in sesquiterpene alkenes: Ylang Ylang, Black Pepper,
Copaiba, Melissa, and Ginger
3.4 ESTERS
An ester is a functional group that results from the reaction between
an alcohol and an acid. Esters have a central carbon atom double
bonded to an oxygen atom, single bonded to the backbone, and
single bonded to a second oxygen atom (see figures 3.5 and 3.6).
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